In recent years, a variety of control systems have been developed and are now in use for automotive vehicle windows. Such systems may include a number of features including blockage detection and "one touch" control.
Blockage detection in such systems may be accomplished by measuring motor current or motor speed changes. More specifically, a foreign object blocking window operation results in a higher current draw by the motor, as well as a slower motor speed. Either of these conditions can be detected to determine window blockage and to halt and/or reverse operation of the drive motor.
In many window control systems, a dedicated input from the window switch is required to continue operation of the window drive motor. However, with "one touch" control, the vehicle window may be driven to a completely open or closed position with only a single, momentary activation of the window switch. Such "one touch" controls are often integrated with the blockage detection feature described above.
However, most such window control systems lack the ability to adapt to changing conditions. More specifically, frictional and mechanical characteristics associated with the window may vary over time due to wear, vibration or other circumstances. Such varying characteristics cause changes in window size and drive motor currents, which are used to effectuate window control. Without the ability to adapt to such changes, many window control systems develop operational problems, including false blockage detection and the inability to completely open or close the window.
U.S. Pat. No. 4,608,637 issued to Okuyama et al. ("the Okuyama '637 patent") discloses a control device for driving road-vehicle electric powered equipment, such as a window. The control device of the Okuyama '637 patent includes a window travel limit adaptive ability and a motor current adaptive ability to overcome the problems described above concerning complete opening and closing of the window as well as false blockage detection.
However, the control device of the Okuyama '637 patent, like other adaptive window control systems, lacks the ability to adapt to travel limits during normal modes of operation. That is, existing adaptive control systems are only capable of adapting to travel limits during a learning mode of operation wherein a dedicated input from an operator is required. Moreover, the control device of the Okuyama '637 patent also lacks any error detection feature associated with its window travel limit adaptive ability.
Thus, there exists a need for a window control system and method having a window travel limit adaptive ability which is operative during the normal mode of window operation and absent a dedicated operator input. Still further, a need exists for a window control system with a window travel limit adaptive ability having an error detection feature associated therewith.